This is all fanmade, and in the pov that lumine is the 'evil'/abyss twin and aether is the 'good' twin helping teyvat. But, Aether finally learns the truth about what happened to khaenri'ah and his sister and finally joins her as he realizes how selfish the Archons/Gods truly are. WARNING THIS MAY INCLUDE SPOILERS!! DO NOT READ UNTIL YOU HAVE FINISHED ALL ARCHON QUESTS OUT IN THE GAME AS OF THE 2.0 UPDATE!

well you get it from the title